Ingestion of wheat, barley, rye and possibly oats, which contain gluten may cause abnormal autoimmune responses, such as celiac disease, wheat allergy and dermatitis herpetiformis, in gluten intolerant individuals. Gluten is a mixture of glutamine- and proline-rich glutenin and prolamin protein molecules. Most of the individuals having the abnormal autoimmune responses express the human leukocyte antigen (HLA) DQ2 or DQ8 molecules. The autoimmune reactions result in the development of small intestinal mucosal villous atrophy with crypt hyperplasia and mucosal inflammation. Symptoms of celiac disease can vary from individual to individual, and may include one or more of fatigue, chronic diarrhea, constipation, malabsorption of nutrients, weight loss, abdominal distension, anemia, as well as a substantially enhanced risk for the development of osteoporosis and intestinal malignancies (lymphoma and carcinoma).
Treatment for gluten intolerance commonly involves a lifelong strict gluten-free diet. However, gluten-free diet is inconvenient, restrictive, and gluten is difficult to avoid. Therefore, effective alternative treatments of gluten intolerance are needed.
A number of bacterial species are known to cause gastrointestinal tract infection. Although current treatment for such infections relies heavily on antibiotics, an increasing number of bacterial infections are found to be resistant to at least some antibiotics. In addition, some bacteria species form endospores that make them especially difficult to eradicate. Gastric proteases such as pepsin are generally unable to kill endospores, for example because of the inability to break down the proteinaceous coat that protects the endospore. Therefore, effective alternative treatments of bacterial infection are needed.